Doc/lib/libgetopt.tex

   1 \section{\module{getopt} ---
   2          Parser for command line options.}
   3 \declaremodule{standard}{getopt}
   4
   5 \modulesynopsis{Parser for command line options.}
   6
   7
   8 This module helps scripts to parse the command line arguments in
   9 \code{sys.argv}.
  10 It supports the same conventions as the \UNIX{} \cfunction{getopt()}
  11 function (including the special meanings of arguments of the form
  12 `\code{-}' and `\code{-}\code{-}').
  13 % That's to fool latex2html into leaving the two hyphens alone!
  14 Long options similar to those supported by
  15 GNU software may be used as well via an optional third argument.
  16 This module provides a single function and an exception:
  17
  18 \begin{funcdesc}{getopt}{args, options\optional{, long_options}}
  19 Parses command line options and parameter list.  \var{args} is the
  20 argument list to be parsed, without the leading reference to the
  21 running program. Typically, this means \samp{sys.argv[1:]}.
  22 \var{options} is the string of option letters that the script wants to
  23 recognize, with options that require an argument followed by a colon
  24 (i.e., the same format that \UNIX{} \cfunction{getopt()} uses).  If
  25 specified, \var{long_options} is a list of strings with the names of
  26 the long options which should be supported.  The leading
  27 \code{'-}\code{-'} characters should not be included in the option
  28 name.  Options which require an argument should be followed by an
  29 equal sign (\code{'='}).
  30
  31 The return value consists of two elements: the first is a list of
  32 \code{(\var{option}, \var{value})} pairs; the second is the list of
  33 program arguments left after the option list was stripped (this is a
  34 trailing slice of the first argument).
  35 Each option-and-value pair returned has the option as its first
  36 element, prefixed with a hyphen (e.g., \code{'-x'}), and the option
  37 argument as its second element, or an empty string if the option has
  38 no argument.
  39 The options occur in the list in the same order in which they were
  40 found, thus allowing multiple occurrences.  Long and short options may
  41 be mixed.
  42 \end{funcdesc}
  43
  44 \begin{excdesc}{error}
  45 This is raised when an unrecognized option is found in the argument
  46 list or when an option requiring an argument is given none.
  47 The argument to the exception is a string indicating the cause of the
  48 error.  For long options, an argument given to an option which does
  49 not require one will also cause this exception to be raised.
  50 \end{excdesc}
  51
  52
  53 An example using only \UNIX{} style options:
  54
  55 \begin{verbatim}
  56 >>> import getopt, string
  57 >>> args = string.split('-a -b -cfoo -d bar a1 a2')
  58 >>> args
  59 ['-a', '-b', '-cfoo', '-d', 'bar', 'a1', 'a2']
  60 >>> optlist, args = getopt.getopt(args, 'abc:d:')
  61 >>> optlist
  62 [('-a', ''), ('-b', ''), ('-c', 'foo'), ('-d', 'bar')]
  63 >>> args
  64 ['a1', 'a2']
  65 >>>
  66 \end{verbatim}
  67
  68 Using long option names is equally easy:
  69
  70 \begin{verbatim}
  71 >>> s = '--condition=foo --testing --output-file abc.def -x a1 a2'
  72 >>> args = string.split(s)
  73 >>> args
  74 ['--condition=foo', '--testing', '--output-file', 'abc.def', '-x', 'a1', 'a2']
  75 >>> optlist, args = getopt.getopt(args, 'x', [
  76 ...     'condition=', 'output-file=', 'testing'])
  77 >>> optlist
  78 [('--condition', 'foo'), ('--testing', ''), ('--output-file', 'abc.def'), ('-x',
  79  '')]
  80 >>> args
  81 ['a1', 'a2']
  82 >>>
  83 \end{verbatim}